package org.nowcoder.leetcode.BTree;

import java.util.Stack;

/**
 * Title  : 669. Trim a Binary Search Tree
 * Source : https://leetcode.cn/problems/trim-a-binary-search-tree/description/
 * Author : XrazYang
 * Date   : 2024-04-23
 */

public class LeetCode_669 {

    private  class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;

        TreeNode() {
        }

        TreeNode(int val) {
            this.val = val;
        }

        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }

    private TreeNode deleteNode(TreeNode root, int key) {
        if (root == null) return null;
        if (root.val == key) {
            if (root.left == null) return root.right;
            else if (root.right == null) return root.left;
            else {
                TreeNode cur = root.right;
                while (cur.left != null) {
                    cur = cur.left;
                }
                cur.left = root.left;
                root = root.right;
                return root;
            }
        }
        if (root.val < key) root.right = deleteNode(root.right, key);
        if (root.val > key) root.left = deleteNode(root.left, key);
        return root;
    }


    /**
     * 朴素解法：遍历筛选不符合条件的结点，再依次删除（击败0.44%）
     */
    public TreeNode trimBST(TreeNode root, int low, int high) {
        Stack<TreeNode> sta = new Stack<>();
        TreeNode current = root;
        while (current != null || !sta.isEmpty()) {
            if (current != null) {
                sta.push(current);
                current = current.left;
            } else {
                current = sta.pop();
                if (low > current.val || current.val > high) {
                    root = deleteNode(root, current.val);
                }
                current = current.right;
            }
        }
        return root;
    }
}
